First — technically speaking — the referendum is not legally binding. In theory, Cameron, who plans to leave by October, could ignore the will of a slight majority of voters, and not make any moves to exit the political and economic bloc.

But Cameron, who led the campaign to remain in the EU, is likely to invoke Article 50 of the Lisbon Treaty, which begins the legal process for leaving the bloc.

“The British people have made the very clear decision to take a different path and as such I think the country requires fresh leadership to take it in this direction,” he said Friday in a televised address outside his residence. “I do not think it would be right for me to be the captain that steers our country to its next destination.”

Once Article 50 is invoked, a series of negotiations would begin about how to disentangle the U.K. from the many EU structures to which it is a party. The process could take two years or more, if both the U.K. and the European Council agree to extend the discussion period.

Cameron has said this process would be irreversible.

“We should be clear that this process is not an invitation to rejoin, it is a process for leaving,” he said in February.

Some have suggested that British leadership could avoid invoking Article 50 all together, and would instead attempt to negotiate a different — not entirely separate — relationship with the EU.

In the more immediate term, markets are going to react in a big way. The Brexit has no historic precedent. No precedent means volatility in markets, probably on a global scale.

If there’s one near-definite result that experts can safely predict around a Brexit, it’s that it increases the amount of uncertainty in markets. Market watchers have predicted a global flight to safer assets — and indeed, that appears to have already begun: Gold futures, the classic safe-haven asset, rose more than 8 percent at one point, before paring some of those gains.

Geoff Caddkick | AFP | Getty Images

Leave.EU supporters wave Union flags and cheer as the results come in at the Leave.EU referendum party at Millbank Tower in central London early in the morning of June 24, 2016.

Asset prices told a story of a shocking turn of events that polls failed to predict and which markets failed to price in correctly:

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